Perry Mick wrote:
Perry Mick wrote:
Well, not exactly. After 5 years and 500 hours of direct-drive,
ducted-fan rotary flying, I did a short first-flight around the
pattern
today with a new configuration: RD1B and a prop.
I am used to getting pushed back in my seat when I apply full
throttle
for takeoff. The open prop seems very sluggish while taxiing, and at
the
start of takeoff roll. I can feel the blades "unstall" after building
up
some speed. This is something I never experienced with the ducted
fan. I
saw 5400 RPM on climbout, higher than before (5100). 5400 was max.
level
flight RPM with the ducted fan, so I expect it will go up to 6000
with
the PSRU. I shed 36 lbs. in the propulsion system doing the
changeover,
and had to remove the weather radar indicator from the panel and the
wx
antenna from the nose (additional 16 lbs. combined) to get the cg
back
(radar needs repair anyway, it's just been balast for a long time).
Climb rate is definitely better (higher revving engine, less weight).
I'm hoping to get at least 180 mph in cruise, 155 was about the best
I
could do with the ducted fan.
Perry
Hey Perry finally tried a PSRU. Got some pictures of the prop? Pitch?
diameter?
RD1B is 2.85:1 right?
Paul Lamar
I had considered a 2.85 that Peter Cowan had for sale awhile back, but I
just couldn't make that ratio work on a pusher (on paper), with my "low" rpm
engine (7000 redline).
RD1B is 2.17 six-planet. I actually was not even thinking about putting
on a PSRU at this time, but with the big fad of going to 2.85 among the RV
crowd, a low-time RD1B went on sale by a guy doing
a conversion to 2.85.
For prop I just looked at what the O-235 LongEZ guys were using and
started with that. The average seems to be around 62" in diameter and 68"
pitch, so that's what I analyzed and built. I was going
to make it two-blade, but I had some prop bolts laying around I wanted
to use, that limited prop hub thickness to 3.5". So I hit on the idea of
making it 3-blade with narrow blade chord. I wanted to
keep the diameter small as I have the thrustline lower 2-3 inches from
stock. I have about 11 inches of ground clearance.
I have some vibration that only showed up after bolting on the prop, so
I assume it's a small imbalance in the prop. But I can't get the dynamic
balancing equipment to converge on a solution. That's
why I kept the flight short. I'm going to try again today at a higher
RPM.
I'll try to take some photos with my cheap digital camera.
I still like the ducted fan, someday I'll build this LSA Solitaire,
where the speed limit is 120 knots.
Perry
Hi Perry,
no plans or dreams to put together a different fan for the Eze?
I thought last time I visited your site, that there where plans for a
different shroud and fan?
Good luck with the optimisation process!!
Thomas J.
I think Perry got tired of having all Long Eze guys kick sand in his face :)
I also think he will improve his MPG greatly.
Paul Lamar
I've been flying the same duct and fan since October 1999. I tried a few things with a different duct in 2000, but that was about it. I had several ideas after that but didn't try anything else. The
website is way out of date. I figured I would have a psru/prop eventually, wasn't even looking for one when this one went on sale. It's about time to get the full utility of my airframe for those
long cross countries that the plane is designed for. Hopefully what I've done will help others. I still like the feel of the ducted fan while taxiing, and at the start of the takeoff roll. Also,
I've made two landings now with the prop, and it takes more power on final than with the ducted fan! Haven't figured that one out yet. The prop is very sluggish in response to throttle changes on
the ground and on final. It's so sluggish at the start of takeoff roll, I can't understand how those RVs get off the ground in such short distances with a fixed pitch prop.
Perry
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